1. Field of Invention
This invention relates to static structures, and more particularly to a modular system for mounting and supporting thermal insulation and exterior cladding on a structure.
2. Background and Description of Prior Art
It is well known in the construction field to build exterior structure walls with plural spaced apart parallel vertical studs of wood or metal. The studs communicate, at a bottom end portion with a wall plate that is anchored to a lower support which may be a building foundation, and at an upper end portion with a ceiling plate that extends generally perpendicular to the studs and parallel with the wall plate. A weather resistive barrier formed of material such as asphalt impregnated paper, plastic sheeting, building wrap or similar product may be attached to outward facing edges of the wall studs, extending from stud to stud and from floor plate to ceiling plate. The weather resistive barrier inhibits flow of air and moisture through any gaps that may exist in the wall assembly.
Exterior cladding, which may also be called “sheathing” in materials such as, but not limited to, plywood, oriented strand board (OSB), wafer board, metallic sheeting, lapboard, gypsum sheathing and the like, may be fastened to the outward facing edges of the wall studs outward of the weather resistive barrier. The exterior cladding also typically extends from wall stud to wall stud and from the wall plate to the ceiling plate. The exterior cladding may provide the exterior surface of the structure or may itself be covered with another exterior cladding, exterior covering or exterior coating.
Services such as plumbing, electrical, tele-communications and the like may be provided for by forming horizontally aligned holes in the studs and placing conduit, or the like, through the horizontally aligned holes. Thereafter, wiring, pipes and the like may be threaded into and through the conduit or directly through the holes as desired.
Commonly, insulation is installed directly against the weather resistive barrier, or directly against the inward facing surface of the exterior cladding depending upon the type of wall assembly, in the spaces between the wall studs extending from the floor plate to the ceiling plate. The insulation may be of various forms including fiberglass batting, mineral wool, recycled paper, cellulose or the like. The object is to “fill” the space between the wall studs to limit thermal transfer from the interior of the structure wall to the exterior of the structure wall, and visa versa depending upon the structure's interior operating conditions and the outside climate.
Alternatively, expanding foam-type insulation or the like may be added to the spaces between the wall studs in place of the fiberglass batting, mineral wool, cellulose or other form of insulation. If expanding foam-type insulation is used, it is desirable to make the expanding foam-type insulation flush with the inward facing edges of the wall studs so that the insulation does not protrude beyond the inward facing edges of the wall studs which may cause interior sheathing such as gypsum board to “bulge” or otherwise not properly “seat” against the inward facing edges of the wall studs.
A vapor barrier such as plastic sheeting or the like may be attached to the inward facing edges of the wall studs extending from wall stud to wall stud and from the ceiling plate to the floor plate enclosing the insulation between the wall studs and between the inner vapor barrier and outer weather resistive barrier. In some instances the vapor barrier may be a surface coating that is applied to the outward facing surface of the interior wall sheathing.
Interior sheathing, such as drywall, gypsum board, paneling or the like is attached to the inward facing edge portions of the wall studs, the floor plate and the ceiling plate and access holes are cut in the interior sheathing to provide access to the electrical boxes, plumbing fittings and the like.
One drawback to such wall framing methods is that such methods create thermal bridges in the structure's walls which decrease the effectiveness of insulation and conduct thermal energy through the wall structure from the inside to the outside, and from the outside to the inside depending upon the outside temperatures and the inside operating conditions.
Although insulation is provided between the wall studs, the studs themselves provide less insulative value and walls formed by such methods are not thermally efficient because thermal transfer occurs through the wall studs. With metal wall studs, such as those commonly used in commercial construction, the effectiveness of insulation between the metal wall studs may be reduced by more than fifty percent (50%).
For example, a wall assembly having exterior cladding and interior sheathing supported by plural parallel spaced apart 2″×6″ wood wall studs therebetween and having T-21 rated fiberglass batting type insulation filling the spaces between the wood wall studs has an effective R-rating of approximately R-18 due to the thermal transfer through the wood wall studs. If the same wall assembly is constructed using steel wall studs between the exterior cladding and the interior sheathing the effective R-value drops to approximately R-8 because of the thermal loss through the steel wall studs.
Even when additional layers of thermal insulation are placed on the exterior of a structure, the thermal effectiveness of such insulation is reduced by the common practice of attaching exterior cladding directly to the outward facing surface of the insulation with metal framing elements that penetrate through the insulation thereunder to attach to the underlying wall studs for structural support.
Adding insulation to the exterior of a structure is also known to reduce condensation within the wall, which occurs when moisture-laden air comes into contact with a surface having a temperature below the dew-point temperature of the moisture-laden air. In a wall assembly, condensation usually occurs during the cold weather months on the inward facing surface (back side) of the exterior cladding when warm moisture laden air from the interior of the structure penetrates the wall assembly and contacts, the cold inward facing surface of the exterior cladding. In warm weather months, the condensation usually forms on the outward facing surface of the insulation by warm air penetrating the wall from the outside and contacting the cooler outward facing surface of the insulation which can lead to moisture saturation of the insulation which degrades the effectiveness of the insulation. Without proper design and engineering, attaching insulation directly to the exterior of a structure can be ineffective and can even be detrimental to the useful life of the wall assembly.
Another drawback to such construction methods is the limited number of options for cladding the exterior of a light-frame structure. Although some variety of exterior claddings are available, such as lap board, metal siding, paneling and the like, such cladding is typically limited to light weight coverings that can be supported by hanger-type wall attachments. Cladding exterior walls with heavy materials such as brick, stone and the like has previously been difficult because the weight of such coverings must be supported by the wall attachments. Overcoming this difficulty leads to additional costs and expenses for larger foundations for vertical support, stronger beams for horizontal support and additional labor costs.
A further drawback to such construction methods is the limited ability to refurbish existing structures by changing the exterior. Generally, when an existing structure is “re-clad” the options available are limited to replacing the existing cladding, or fastening a similar type of cladding over the top of the existing cladding. Unfortunately, at times this is not feasible because the existing cladding is too deteriorated to allow stable attachment of the new cladding system. Further, in some instances the vertical “plumbness” of an exterior wall might be so poor that it is not feasible or practical to attach a new exterior cladding to the existing structure. Finally, attaching a new exterior cladding has the ability to alter the building's footprint sufficiently to cause property line set-back problems by extending the building's walls outwardly.
Evolving construction standards with increased emphasis on energy efficiency, “being green” and limiting greenhouse gas emissions have required construction methods and techniques to likewise change to focus on the energy efficiency of structures. One way to increase the energy efficiency of a structure is to add insulation to the exterior of the structure. Another is to minimize, or if possible eliminate thermal bridges that allow energy loss. A third is to improve moisture management which improves durability and thermal performance of the wall assembly. An even more effective solution is to do all three; add insulation to the exterior of a structure while effectively managing moisture and eliminating and minimizing thermal bridges. The combination of these efforts is known as “continuous insulation” which is defined in various building codes, such as, but not limited to, ASHREA 90.1 as insulation that is uninterrupted by framing members, except fasteners (screws, nails) and is installed either inboard or outboard of the wall.
The precise definition of “Continuous Insulation” as set forth in the proposed Seattle Energy Code of 29 Apr. 2010 with which Applicants are most familiar, defines continuous insulation as follows:                CONTINUOUS INSULATION (C.I.): Insulation that is continuous across all structural members without thermal bridges other than fasteners (i.e., screws and nails) and service openings. It is installed on the interior or exterior or is integral to any opaque surface of the building envelope. Insulation installed between metal studs, z-girts, z-channels, shelf angles, or insulation with penetrations by brick ties and offset brackets, or any other similar framing is not considered continuous insulation, regardless of whether the metal is continuous or occasionally discontinuous or has thermal break material.        
What is needed is a system that allows exterior cladding to be installed on new structures and onto existing structures, and allows the walls to be insulated having a high degree of thermal insulation while minimizing or eliminating thermal bridges and moisture management problems. The system must accommodate a variety of exterior claddings and must allow the structure to be provided with a new appearance, including an appearance of being constructed a brick, stone or the like. The system must comply with evolving construction standards including the new ASHRE 90.1 standards, including the standards for continuous installation. The system must be economical and efficient and provide sufficient flexibility and structural integrity to allow a user to clad the exterior of a structure as desired and simultaneously preserve the desirable features of known light frame construction methods and systems.
Our system overcomes various drawbacks of known construction apparatus, methods and techniques by providing a modular system that preserves user flexibility in the exterior cladding of a structure and maximizes the insulative capabilities by providing a continuously insulated structure having no or minimal thermal bridges that allow thermal energy loss.
Our system provides vertical girders that are attached to the underlying structure in a manner that the vertical girders are thermally isolated from the underlying structure to prevent creation of thermal bridges. The vertical girders secure insulation to the structure and provide an anchor for the exterior cladding which may be either directly or indirectly mounted thereto.
Rigid panels of insulation between the inner surface of the vertical girders and the outward edges of the vertical wall studs, or exterior of the structure, enhance energy efficiency of the structure. The rigid panels may have a core of expanded foam-type insulation and may be covered with a flame resistant covering. Joints between adjacent rigid insulative panels are sealed to eliminate any gaps through which air and moisture might otherwise pass.
A wall panel hanging system fastened to outward facing surfaces of the vertical girders provides a “U” channel upon which exterior cladding or wall panels may be releasably secured. A desired exterior cladding may be fastened to an exterior surface of the wall panels. Corner elements carrying complimentary sections of the desired exterior cladding are supported by the system at the structure corners.
Flexibly resilient grout having a visual appearance of masonry grout fills the gaps between the cladding elements to accommodate thermal expansion and unforeseen vibrations that might otherwise allow cracking therein.
A rainscreen between inner surface of the exterior cladding and the outer surface of the insulation provides a pressure equalized drain cavity that prevents moisture from passing from the exterior into the wall assembly, reduces condensation, and properly manages moisture. The pressure equalized drain cavity is configured to comply with fire standards to prevent formation of a “chimney” between the inner surface of the exterior wall cladding and the outer surface of the insulation.
Thermal isolators reduce thermal transfer between metal to metal connections and create a “bottle neck” for heat transfer between the vertical girders and the underlying structure and maximize the effectiveness of the insulation.
Our system increases the “effective R Value” of structures by providing a more energy efficient wall structure that loses less heat through thermal conduction through the wall structure.
Our system lowers the likelihood of condensation within the wall structure effectively manages moisture and minimizes energy losses related to thermal bridging.
Further, our system satisfies evolving and changing building codes and regulations, such as but not limited to ASHRAE 90.1 standards which are the baseline energy efficiency guidelines used worldwide for promotion of energy efficiency, energy conservation and “greenness”.
Our system allows the exterior of a structure to be clad in a material that has the appearance and texture of masonry, brick, stone and the like, but the cladding system does not have the weight of such construction and therefore the foundation and other underlying support structures of the building need not have the massiveness or therefore the cost and expense of support structures that would be necessary to support construction with such heavy materials.
Our invention does not reside in any one of the identified features individually, but rather in the synergistic combination of all of its structures, which give rise to the functions necessarily flowing therefrom as hereinafter specified and claimed.